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Marijuana users’ risk of deadly complication doubles after aneurysmal subarachnoid hemorrhage

Among people with an aneurysmal subarachnoid hemorrhage ( aSAH ) stroke recent Marijuana users were more than twice as likely to develop a dangerous complication that can result in death or greater disability.

The study is the largest to examine the impact of Tetrahydrocannabinol ( THC ), the psychoactive component of Marijuana on complications after an aneurysmal subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage is a type of stroke resulting in neurological disability in about 66% of people and death in about 40%.

The immediate treatment of an aneurysmal subarachnoid hemorrhage focuses on stopping and preventing further bleeding. However, despite treatment, in the 14 days following an aneurysmal subarachnoid hemorrhage, many patients may develop worsening symptoms ( such as speech problems or difficulty moving ). This is caused by blood from the initial stroke irritating blood vessels, causing a vasospasm, resulting in more brain damage. This complication, called delayed cerebral ischemia, is a leading cause of death and disability after an aSAH stroke.

Researchers have analyzed data on more than 1,000 patients who had been treated for aneurysmal subarachnoid hemorrhage at Barrow Neurological Institute between January 1, 2007 to July 31, 2019. All patients had been treated to stop the bleeding either via 1) open surgery to clip off the base of the aneurysm, or, 2) noninvasively, by threading a slim tube through a blood vessel to the base of the aneurysm and releasing coils that fold to fill in the space and provide a barrier to further bleeding.

Urine toxicology screening was performed on all patients admitted with ruptured aneurysms. The study compared the occurrence of delayed cerebral ischemia in 46 people ( average age of 47 years; 41% female ) who tested positive for THC and 968 people ( average age 56 years, 71% female ) who tested negative for THC. A positive urine screen for THC reflects Cannabis exposure within three days for a single use to within approximately 30 days for frequent heavy use.

The recent Cannabis users did not have significantly larger aneurysms or worse stroke symptoms when admitted to the hospital, and they were not more likely to have high blood pressure or other cardiovascular risk factors than patients who screened negative for THC. However, recent Cannabis users were significantly more likely to have also tested positive for other substances, including Cocaine, Methamphetamines and tobacco, compared to the patients who screened negative for THC.

Among all participants, 36% developed delayed cerebral ischemia; 50% were left with moderate to severe disability; and 13.5% died.

After adjusting for several patient characteristics as well as recent exposure to other illicit substances, patients who tested positive for THC at last follow up were found to be: 2.7 times more likely to develop delayed cerebral ischemia; 2.8 times more likely to have long-term moderate to severe physical disability; and 2.2 times more likely to die.

The study did not specifically address how Cannabis raises the risk of vasospasm and delayed cerebral ischemia.
Cannabis may impair oxygen metabolization and energy production within cells. When stressed by a ruptured aneurysm, the cells are much more vulnerable to changes that affect the delivery of oxygen and the flow of blood to the brain.

The study’s limitations include being conducted retrospectively at a single institution and not being a head-to-head analysis of people who use Marijuana and those who don’t. ( Xagena )

Source: Stroke, 2022